Rectal Endocavitary Irradiation
Endocavitary irradiation (“contact therapy”) is a specialized method of delivering a very high dose of radiation therapy to a very small volume of tissue in the rectum. It is an effective treatment for early-stage rectal adenocarcinoma that is limited to the submucosa, with a probability of cure in the range of 90%.
The treatment is given with a hand-held X-ray tube that delivers 50 keV radiation, which penetrates to a depth of approximately 1 cm. The treatment is given through a proctoscope that is designed to be used with the treatment machine. This specialized equipment is available in a very few radiation oncology departments throughout the United States. The treatment technique was initially developed in France, where Dr. William Mendenhall studied with Dr. Jean Papillon, one of the originators of the technique, to learn how to deliver this form of therapy.
The treatments are given in high doses (approximately 3000 roentgens per treatment) to this limited area every 2 weeks for a total of four outpatient treatments. Aside from some local anesthetic in the form of lidocaine injections, no other anesthesia is required.
Before any treatment is started, the recommended treatment, the reasons it is recommended, the procedures to be carried out, the expected or possible side effects or complications, and the expected benefits are all explained to the patient and family. The patient must give permission for treatment, based on this knowledge (“informed consent”), before treatment is given.